The 1990's decade has been marked by a technological revolution driven by the convergence of the data processing industry with the consumer electronics and communications industries. This advance has been even further accelerated by the extensive consumer and business involvement in the internet over the past few years. As a result of these changes, it seems as if virtually all aspects of human endeavor in the industrialized world requires human computer interfaces. There is a need to make computer directed activities accessible to a substantial portion of the world's population which, up to a few years ago, was computer illiterate, or at best computer indifferent. In order for the vast computer supported market places to continue and be commercially productive, it will be necessary for a large segment of computer indifferent consumers to be involved in computer interfaces. Thus, the challenge of our technology is to create interfaces to computers which are as close to the real world as possible.
In this connection, there is the touch screen or touch panel. It is easy to use because it allows the user to point directly with his finger to make selections which move a cursor or other element around a display screen. The touch panel in various forms has been in use for several years. Several different technologies have been involved in touch panels. Original touch panels used a series of infrared LEDs and light sensors, such as photodiodes, to provide low resolution panels of up to 50 resolvable positions. The LEDs and sensors form a grid of invisible light beams which the finger breaks to, thus, indicate its position. The capacitively coupled touch panels were able to develop a resolution of about 100 resolvable positions. Higher resolution touch screens have been developed using a variety of technologies from sound waves reflected off fingers to conductive/resistive layers separated by insulative material broken down by touch.
While direct touch screens are simple to use, they do have some eye/hand coordination shortcomings. First, while the finger is a natural pointer, because of its relatively wide dimensions and difficulty in making precise movements in small increments, it has limitations in making movements and selections in high information density/high resolution screens. In this connection, the finger and like direct pointers are also hampered by parallax: if the conventional touch panel is 1/4+L " to 1/2+L " from the display, then the user's fingers tend to touch the position on the panel that is aligned with their eyes and the selected point on the display screen and not the position on the touch panel directly perpendicular to the selected point on the display screen.